Positioning Assemblies vs Extended Positioning Assemblies

[DarrenStorey]

We are currently switching to positioning assemblies when publishing Catia and Creo. I understand that "extended" positioning assembies should be used for Creo, if there are assembly features.

Please would sombody mind to explain technically what the difference is, and roughly what is happening in the background?

What are the downsides of using "extended" positioning assemblies, over standard positioning assembies?

I've read a few presentations on this subject, but have yet to find anything which addresses this particular question.

Many thanks - Darren

[DavidCobb]

Just wanted to chime in that we are still trying to get our heads around it and would love to hear the explanation (even at the "... For Dummies" level!) as well.

[LoriSood]

I'm not sure if you've seen this, but the following article explains the basic differences between the two:

https://www.ptc.com/appserver/cs/view/solution.jsp?n=CS130256

The extended positioning assemblies will publish based on a specified simplified representation name. The main disadvantage over positioning assemblies is that it still downloads the dependencies to the publish workspace. Hence publish times may take longer than for positioning assemblies.

[DarrenStorey]

Lori,

thanks for the link, it helps a bit. I found this page a bit of a challenge to fully understand however. See attached diagram which represents my interpretation of this information in a more digestable format. Confirmation appreciated.

Is it therefore true to say for extended positioning assemblies the CAD worker will only download models which are affected by the assembly features? So If I have a 1000 part assembly to publish, and only one of the lowest level assemblies with just 2 parts has a feature cut, then only this one low level assembly (With it's 2 parts) will be downloaded when publishing the the MA?

But if a feature cut appears in the top level assembly, all 1000 parts will need to be downloaded to publish as extended positioning assembly. In this instance it would therefore take roughly the same amount of time to publish as a standard job? Or is the system smart enough to know which of the 1000 parts are affected by the assembly cut, and just download those with affected geomoetry?

Does the same apply to additive assembly features?

Regards

Darren

[jzupfer]

Hello,

A search for "positioning assembly" in the Windchill Help Center resulted in return of 13 topics, including the following, which seem to answer some of the questions above:

Publishing Creo Parametric and CATIA V5 Assemblies as Positioning Assemblies

Configuring Publishing of Extended Positioning Assemblies

If you review this content, I'd be very interested in your feedback regarding what could make it more useful.

Thanks,

Jane

Jane Zupfer
VP, Enterprise Products Publications
E -

PTC.com

[DarrenStorey]

Hi Jane,

I did the usual searches. There is not so much related explicitly to extended positioning assemblies, specifically the pros/cons of using them. I think I've got my head around standard positioning assemblies already.

To be honest I'm still struggling a bit (and my colleagues) to confidently define our publishing stratergy for Creo. The documentation helps me configure once I know what we should be doing, but it's not helping much to make the strategic decisions. I'm not a CAD guru, so maybe these knowledge gaps are holding me back.

We'll make a collection of tests, I'm sure it will help clarify.

Regards - Darren

[TomU]

There were multiple presentations on this topic last year at PTC Live Global, and several more this year. (Last year's presentations are available on the PTC User website. This year's are currently only available to those who attended.)

Basically, a positioning assembly will only load the top level assembly file on the publisher. It will NOT download or open any of the dependents (parts or assemblies). This makes publishing very fast. For extended positioning assemblies, the entire assembly and all related parts need to be downloaded and physically opened on the publisher, so the load time advantage is lost, but the file(s) produced are still much less than what would be produced if positioning assemblies weren't used at all.

[MartinHill]

I too, like Darren am still in the dark regarding how to use Advanced Positioning assemblies.

I understand the documentation that has been posted but there are still several unanswered questions.

1. The PTC documentation talks about supported for a limited number of Assembly level features but does not define what these are. Any ideas?

2. What about other assembly level things that don't change geometry such as assembly level colours or assembly level datumns?

3. If positioning assemblies are used with "Latest" configuration specification does that mean that when you look at the representation of an older iteration you will see the structure of the old assembly but the latest representation of the components? Does this mean that non latest representations serve no purpose if you use latest as the configuration specification?

Regards,

Martin Hill

[jzupfer]

Thank you for the additional information and the list of unanswered questions. I'm following up with Development and the Product/Segment owners to get information we can use to enhance the documentation and to answer the questions that Martin posed. If those on this thread have additional suggestions about what should be covered in the doc, please let me know.

Regards,

Jane

[BartonC.Fiske]

Some updates on this topic....am still researching questions 1 & 2, which are somewhat related and are not identifiable from the current documentation or online articles. To some degree the responses will be use case specific and needs some thinking through in terms of what will publish, what won't and/or why.

For question 3 and it's follow-on, here's some additional guidance:

3. If positioning assemblies are used with "Latest" configuration specification does that mean that when you look at the representation of an older iteration you will see the structure of the old assembly but the latest representation of the components?

1. Yes. When a Positioning Assembly branch-link is expanded in Creo View, WVS uses an algorithm that attempts to determine the most relevant sub-assembly/component Representation to use and will effectively incorporate the default derived Representation from the Latest version/iternation of the referenced EPMDocument.

Does this mean that non latest representations serve no purpose if you use latest as the configuration specification?

A. The Positioning Assembly concept is designed to address problems relating to publishing performance for the largest unchanging top-level assembly structures, to remove the need to constantly republish them in order to see the latest Representation of them. It is not designed or able to provide the exact structure Representation in all cases, in these cases, full geometry publishing is required.

Regards,

-Barton